Restoring Accessibility During Urban Rail Disruptions via Bus Network Redesign
Zihao Guo, Andrea Araldo, Mounîm A. El Yacoubi
TL;DR
The paper addresses restoring accessibility during Urban Rail Transit (URT) disruptions, with particular emphasis on suburbs where alternatives are sparse. It proposes a bus network redesign that extends existing lines and reallocates buses to maximize accessibility, implemented via a two-stage heuristic and an integer-programming formulation. The surrogate objective balances accessibility improvements with extension-distance costs, and the approach is validated in two Parisian suburbs, showing superior accessibility recovery and reduced travel distance compared with conventional replacement buses, even without additional vehicles. This work foregrounds accessibility as the guiding criterion in disruption remediation and offers a scalable tool for resilience planning in PT networks.
Abstract
In broad terms, accessibility measures opportunities reachable (such as shops, residents, etc.) within a given time frame. Urban Rail Transit (URT) plays a crucial role in providing accessibility, but it is susceptible to disruptions. In city centers with dense public transport (PT) networks, travelers can often find alternative lines. However, in suburbs where PT is sparse, disruptions have a more significant impact on accessibility. The traditional approach consists in deploying bridge and replacement buses to mitigate URT disruptions without specific care to accessibility. Yet, the question arises: is this approach the most effective way to restore accessibility? To the best of our knowledge, our paper is the first to propose a bus re-routing method with the objective of restoring accessibility during URT disruptions. We formulate an integer program and develop a two-stage heuristic algorithm to maximize restored accessibility. The efficacy of our method is always the present assessed in Évry-Courcouronnes and Choisy-le-Roi, France. The results show that, compared to conventional replacement methods, our strategy improves accessibility in particular in the areas most affected by the disruption. Such results are observed even when no additional vehicles are deployed, and at the same time, achieving a reduction in the kilometers traveled. Despite it is well understood that accessibility is the most relevant benefit a transportation system can produce, this aspect is reflected by the traditional approaches in remediation to disruption. With this work, we show instead how to make accessibility the main guiding principle in remediation.